1. Technical Field
The present invention relates to an ink jet recording apparatus for recording images on a recording medium by discharging ink from an ink cartridge to the recording medium through a nozzle, and more particularly, to a circuit and method for detecting whether an ink cartridge is mounted in an ink jet recording apparatus and the type of ink cartridge mounted in the ink jet recording apparatus.
2. Background Art
Substantial developments have been made in the field of electronic recording technology. Specifically, a wide variety of highly efficient recording systems currently available which are capable of recording characters and images onto a recording medium such as, for example, paper and overhead projection film in a rapid and accurate manner. Thermal ink jet recording systems are particularly popular in this regard primarily because they exhibit various advantages such as, for example high printing speed, low noise, easy color printing, simply construction and low price. The concepts and operational principles of thermal ink jet recording systems are well described, for example, in U.S. Pat. No. 5,138,342 for Ink Jet Cartridge And Ink Jet Recording Apparatus Employing The Same issued to Kurata et al., and U.S. Pat. No. 5,500,664 for Ink Jet Recording Apparatus And Detachably Mountable Ink Jet Cartridge issued to Suzuki et al., all of which are incorporated herein by reference.
In general, an ink jet cartridge is detachably mounted on a recording head carriage assembly which supports a recording head, and traverses the recording head across the width of a recording medium in line recording operation. An ink jet cartridge is typically constructed in an unitary, detachable cartridge which contains an ink container for containing the ink, drop generating structures and electrically connections adapted for electrically coupling a recording head to the ink jet recording apparatus which provides drop generating energy in response to information signals generated by the ink jet recording apparatus. The principle behind this type of ink jet recording apparatus is the generation of the thermal pressure wave the ink container and subsequent emission of ink droplets from the ink container through a plurality of nozzles arranged vertically at a front end of a recording head. The thermal pressure wave is generated by selected heating elements installed in the nozzles, which heat the ink contained within the nozzles until the ink is ejected through an ejection orifice of the nozzles to produce a flying droplet of the ink. The droplet is deposited on the recording medium so that a desired character and image can be formed.
When the ink in the ink container is used up, however, the entire ink jet cartridge including a recording head needs to be replaced. This is required because the ink jet cartridge is typically constructed in a unitary structure regardless of whether such an ink jet cartridge involves a relatively large difference between the period in which the ink in the ink container is used up and the service life of the recording head. Although there has been proposed construction of an ink jet cartridge in which the ink container is detachably mounted to a recording head so as to permit replacement of the ink container and the recording head separately at different times, the ink jet cartridge still needs to be taken out from the ink jet recording apparatus for replacement of an entire ink jet cartridge or an individual part of the ink jet cartridge. Accordingly, it is necessary for the ink jet recording apparatus to be able to efficiently detect whether a new or replaceable ink cartridge is mounted on a recording head carriage for recording characters and images on a recording medium. However, not all ink jet recording systems are capable of efficaciously detecting a replaceable ink cartridge mounted thereon. More often, users tend to throw out the old ink cartridge but forget to mount a new ink cartridge for replacement. In such a situation, the recording operation is performed without the ink container mounted thereon. This, however, is not a desirable situation because air may be introduced into the ink passageway and contribute to the ink ejection failure.
Unfortunately, conventional ink jet recording apparatus requires additional detection pins mounted in the ink cartridge to detect the presence or absence of an ink container or a recording head. For example, U.S. Pat. No. 5,212,502 for Ink Jet Print Head Mounting Mechanism issued to Bowling requires both an ink jet cartridge and a carriage to contain a complementary panel of electrical contacts to determine whether the ink jet cartridge is mounted on the carriage. In Suzuki et al., U.S. Pat. No. 5,500,664 for example, a pair of detection pins are mounted on side surfaces of an ink cartridge holder to detect the presence or absence of an ink container. If additional detection pins are mounted in the ink cartridge, as I have observed however, a railroad is also required to connect the ink cartridge to the detection pins which undesirably increase the number of electrical pins in a connector. Further, even if additional detection pins are required to detect the mounting of a replaceable ink jet cartridge mounted on a carriage, it has also been my observation that the conventional ink jet recording apparatus is still unable to distinguish the type of an ink jet cartridge mounted therein. In other words, the conventional ink jet recording apparatus is only capable of detecting whether an ink cartridge is mounted on a carriage, and is not capable of detecting whether a mounted ink jet cartridge is one is a mono ink cartridge an a color ink cartridge.